1. Field of the Invention
The present invention pertains to chemical dispensers. More specifically, to an additive dispenser attachable to a showerhead or a shower pipe.
2. Description of the Related Art
Attachment devices for showerheads are well known and provide a method for dispensing an additive such as aromatic oil or medication into shower water. The devices previously proposed either lack the ability to accurately control the flow rate of the additive, aromatic oil or medication, into the water, or those devices that provide such control generally are of very complex construction and, hence, are too expensive to manufacture. Furthermore, they are cumbersome to use and take up considerable space.
For instance, U.S. Pat. No. 4,358,056 discloses a method to control the rate by which the additive is introduced into the water prior to the water entering the showerhead, i.e. the additive is mixed with water under pressure. However, the device requires the use of a mixer coupling and three different valves. An additional disadvantage of this and many similar devices described in the prior art is that the additive is mixed with the water prior to the water entering the showerhead. Most commercial showerheads are fitted with various parts made of synthetic rubber, and additives such as aromatic oils cause significant swelling of these rubber parts, thus causing damage to the showerhead.
U.S. Pat. No. 4,131,232 and 6,923,384 disclose two very similar liquid additive dispensing devices in which the additive is added to the shower water after the water exits the showerhead. Both devices use gravity as the force to cause the flow of the additive from a reservoir into the shower water. However, with both devices the additive flows into the water stream as discrete droplets, which is undesirable in many applications. For instance, in one potential type of application, namely aromatherapy, the amount of aromatic oil that is needed for a shower of typical duration is extremely small, generally of the order of less than 0.5 ml per minute or approximately 10 drops per minute. Therefore, if the oil is added in the form of discrete droplets, the aroma effect will be very intermittent, with a sudden burst of strong aroma followed by a period of several seconds with no aroma, a result, which is generally undesirable.
Furthermore, none of the above-mentioned patents disclose a specific method for controlling the flow rate of oil. Simple valves such as needle valves or pinch valves are not capable of providing adequate flow control at the very low flow rates that are required to dispense aroma oils or other additives such as medication. Electronically operated valves may provide adequate control of the flow rate, but such valves are too expensive for most consumer applications. Accurate and reliable control of the additive flow rate is important in many applications. For instance, in the case where bath oil or essential oil is added to shower water to generate an aroma effect, there is a need to control the flow rate because the intensity of the aroma is influenced by several factors such as the type of oil and the water temperature and the preference for different aroma intensities (strong, medium, mild) varies among users. The need to control the additive flow rate is not limited to essential oils and bath oils, but also applies to other additives such as medications.
The present invention provides for a shower additive dispenser which delivers a continuous, i.e. non-intermittent flow of an additive to shower water at extremely low flow rates, and which is capable of controlling the flow rate over a wide range using only one moving part.